Light emmiting diode chip

ABSTRACT

A light emitting diode (LED) chip including a first type semiconductor layer, an light-emitting layer, a second type semiconductor layer, a current blocking layer, a transparent conductive layer and an electrode is provided. The light-emitting layer is disposed on the first type semiconductor layer. The second type semiconductor layer is disposed on the light-emitting layer. The current blocking layer is disposed on the second type semiconductor layer. The transparent conductive layer is disposed on the second type semiconductor layer and covered the current blocking layer. The electrode is disposed on the transparent conductive layer corresponding to the current blocking layer. The current blocking layer and the electrode respectively have a first width and a second width in a cross section view, and the first width of the current blocking layer is larger than the second width of the electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of and claims thepriority benefit of a prior application Ser. No. 13/655,534, filed onOct. 19, 2012, now pending. The prior application Ser. No. 13/655,534claims the priority benefit of Taiwan application serial no. 100138435,filed on Oct. 24, 2011. This application also claims the prioritybenefits of U.S. provisional application Ser. No. 61/944,061, filed onFeb. 25, 2014. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a light-emitting device and more particularlyrelates to a light-emitting diode chip having a current blocking layer.

2. Description of Related Art

Due to the recent gradual decrease in fossil energy, and consequentlythe growing demand for energy-saving products, the light-emitting diode(LED) technology has made significant progress.

Under conditions of instability of the oil price, many countries aroundthe world have actively engaged in development of energy-savingproducts, and the application of light-emitting diodes in energy-savingbulbs is a product of this trend.

In addition, with the advancement of light-emitting diode technology,applications of white or other color (blue, for example) light-emittingdiodes get more widespread.

As the light-emitting diode technology matures over time, there are moreand more applicable areas. The applications of light-emitting diodes tolighting includes residential areas: wall lamps, nightlights (theearliest field for using light-emitting diode as light source due to lowrequirement for brightness) auxiliary lights, garden lights, readinglights; utility areas: emergency lights, hospital bed lights; businessareas: spotlights, downlights, light bars; outdoor areas: buildingexteriors, solar lights; and light shows, etc.

In addition to advantages of light-emitting diodes such as low powerconsumption, mercury free, long life, and low carbon dioxide emissions,the environmental policy of governments around the world banning the useof mercury has also encouraged researchers to delve into R & D andapplication of white light-emitting diodes. While the global trend ofenvironmental protection rises, the light-emitting diode regarded as agreen light source is in line with global mainstream trends. As pointedout previously, it has been widely used in 3C product indicators anddisplay devices; also with the increase in production yield oflight-emitting diodes, unit manufacturing costs have been greatlyreduced, therefore demand for light-emitting diodes keeps increasing.

As described above, the development of high-brightness light-emittingdiodes has become the focus of research and development of companiesaround the world at this moment; however, current light-emitting diodesare still flawed in application design, so that it is hard for theluminous efficiency to be optimal.

SUMMARY OF THE INVENTION

The invention provides a LED chip, capable of enhancing the luminousefficiency of the LED chip.

The LED chip of the invention includes a first type semiconductor layer,an light-emitting layer, a second type semiconductor layer, a currentblocking layer, a transparent conductive layer and an electrode. Thelight-emitting layer is disposed on the first type semiconductor layer.The second type semiconductor layer is disposed on the light-emittinglayer. The current blocking layer is disposed on the second typesemiconductor layer. The transparent conductive layer is disposed on thesecond type semiconductor layer and covered the current blocking layer.The electrode is disposed on the transparent conductive layercorresponding to the current blocking layer. The current blocking layerand the electrode respectively have a first width and a second width ina cross section view, and the first width of the current blocking layeris larger than the second width of the electrode.

In an embodiment of the invention, the ratio of the first width to thesecond width ranges from 1.4 to 2.6.

In an embodiment of the invention, the current blocking layer includes aplurality of high refractive index layers and a plurality of lowrefractive index layers, and the high refractive index layers and thelow refractive index layers are alternately stacked.

In an embodiment of the invention, the high refractive index layersinclude a first high refractive index layer and a second high refractiveindex layer, and the low refractive index layers include a lowrefractive index bottom layer, a first low refractive index layer and asecond low refractive index layer. The low refractive index bottom layeris disposed between the second type semiconductor layer and the firsthigh refractive index layer. The first low refractive index layer isdisposed between the first high refractive index layer and the secondhigh refractive index layer. The second low refractive index layer isdisposed between the second high refractive index layer and thetransparent conductive layer.

In an embodiment of the invention, the thickness of the low refractiveindex bottom layer is larger than the other refractive index layer.

In an embodiment of the invention, the thicknesses of the highrefractive index layers are 0.25λ/n_(h), the thicknesses of the firstlow refractive index layer and the second low refractive index layer are0.25λ/n_(l), the thicknesses of the low refractive index bottom layer is1.75λ/n_(l), where λ is wavelength of a light emitted from thelight-emitting layer, n_(l) is a refractive index of the low refractiveindex layers, and n_(h) is a refractive index of the high refractiveindex layer.

In an embodiment of the invention, the high refractive index layersfurther comprise a high refractive index top layer disposed between thesecond low refractive index layer and the transparent conductive layer.

In an embodiment of the invention, the thicknesses of the highrefractive index layers and the high refractive index top layer are0.15λ/n_(h), the thicknesses of the first low refractive index layer andthe second low refractive index layer are 0.45λ/n_(l), the thicknessesof the low refractive index bottom layer is 0.6λ/n_(l), where λ iswavelength of a light emitted from the light-emitting layer, n_(l) is arefractive index of the low refractive index layers, and n_(h) is arefractive index of the high refractive index layer.

In an embodiment of the invention, a material of the high refractiveindex layers include titanium dioxide (TiO₂).

In an embodiment of the invention, a material of the low refractiveindex layers include silicon dioxide (SiO₂).

In an embodiment of the invention, a material of transparent conductivelayer includes an element selected from a group consisting of indium-tinoxide (ITO), zinc oxide (ZnO), indium-gallium oxide (IGO), aluminiumdoped zinc oxide (AZO), nickel oxide (NiO), ruthenium dioxide (RuO₂),and graphene.

Based on the above, the LED chip of the invention could cause that thereflectivity of the light incident toward the second electrode with asmall incident angle and the transmittance of the light propagatingtoward the neighborhood of the second electrode would be optimized byadjusting the arrangement and thickness of each of a plurality of highrefractive index layers and a plurality of low refractive index layersso as to enhance the light extracting efficiency or the luminousefficiency of the LED chip.

To make the aforementioned and other features and advantages of theinvention more comprehensible, several embodiments accompanied withdrawings are described in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate exemplaryembodiments of the invention and, together with the description, serveto explain the principles of the invention.

FIG. 1 shows a schematic diagram of the structure of the prior art;

FIG. 2 shows a schematic diagram of the structure according to apreferred embodiment of the present invention;

FIG. 3 shows a schematic diagram of the structure according to apreferred embodiment of the present invention;

FIG. 4 shows a cross-section view of the structure according to apreferred embodiment of the present invention;

FIG. 5 shows a cross-section view of the light-emitting diode chipaccording to a preferred embodiment of the present invention;

FIG. 6 shows a cross-section view of the light-emitting diode chipaccording to another preferred embodiment of the present invention;

FIG. 7 shows a schematic view of light path of the light-emitting diodechip show in FIG. 6;

FIG. 8 shows another schematic view of light path of the light-emittingdiode chip show in FIG. 6;

FIG. 9 is a ratio of the first width to the second width—enhancement oflight output power (LOP) rate curve diagram of the light-emitting diodechip show in FIG. 6;

FIG. 10 shows a schematic view of current flow of the light-emittingdiode chip show in FIG. 6;

FIG. 11 shows a cross-section view of the light-emitting diode chipaccording to yet another preferred embodiment of the present invention;

FIG. 12 is an incident angle-reflectivity rate curve diagram of thelight-emitting diode chip show in FIG. 6 and FIG. 11; and

FIG. 13 is an incident angle-transmittance rate curve diagram of thelight-emitting diode chip show in FIG. 6 and FIG. 11.

DESCRIPTION OF THE EMBODIMENTS

In practical applications, light-emitting diodes are often combined aslight-emitting diode array modules, which arrange a large number oflight-emitting diode chips on the substrate and obtain a betterlight-emitting effect by taking advantage of quantity. However, such away of arranging light-emitting diode chips, in addition to problems ofcooling that occur most frequently, how to further enhance thelight-output efficiency is the subject that we should face and thinkabout in this field.

In the prior technologies, as shown in FIG. 1, light-emitting diodechips are arranged side by side on a large substrate, and connected toone another by wire bonding to form a light-emitting matrix. FIG. 1includes a substrate 10 and a plurality of light-emitting diode chips20; the light-emitting diode chips 20 align neatly in the form of amatrix. In this arrangement, except light emitting from top surface ofchips and the light-emitting diode chips 20 at four corners having twosides that light output there from without being shielded, the rest oflight emitting from side walls of the light-emitting diode chips 20 aremutually shielded by adjacent chip; as a result, light output from sidesaround the chip is undoubtedly a waste and lighting efficiency of thelight-emitting matrix is low.

Refer to FIG. 2 and FIG. 3, which shows a schematic diagram of thestructure according to a preferred embodiment of the present invention.As shown in the in FIG. 2 and FIG. 3, the high-voltage light-emittingdevice In the invention comprises a substrate 10 and a set oflight-emitting diode chips 20.

Wherein, the set of light-emitting diode chips 20 are located on thesubstrate 10 and have a number of 18 to 25; in addition, thelight-emitting diode chips 20 have an interleaved or staggeredarrangement that each of the light-emitting diode chips 20 is notaligned or mis-aligned with adjacent one, therefore the periphery ofoverall light-emitting diode chips 20 takes a form of staggered regularor irregular zigzag, as a non-matrix arrangement. Under thisarrangement, in addition to light output from the top surface of thelight-emitting diode chips 20 which occupied about 60% to 80% area ofthe substrate 10 can output light well, light output from the sides ofthe light-emitting diode chips 20 can also be used.

Comparing FIG. 2 and FIG. 3 with FIG. 1, it is clearly understood thatthe present invention enhances the efficiency by adjusting thearrangement of the light-emitting diode chips 20 in order to achieve thebest lighting efficiency for the same production costs.

In the invention, the light-emitting diode chips 20 are connected inseries. Refer to FIG. 4, which shows a cross-section view of thestructure according to a preferred embodiment of the present invention.As shown in the FIG. 4, the light-emitting diode chips 20 are spread onthe substrate 10 and electrically connected to one another in series bybonding metal wires. Because the voltage of each of the light-emittingdiode chips 20 is about 3.1 to 3.5 volts and the number of chips of aset is about 18 to 25, the total driving voltage of the light emittingdevice having a set of light-emitting diode chips In the invention isabout 55.8 to 87.5 volts when the chips are connected in series, thoughit is suggested that the voltage had better keep within the range from70 to 75 volts which is a more appropriate voltage range. And inaddition to connect in series, light emitting chips 20 can also beconnected in parallel or series-parallel depending on the voltagerequirement of the light emitting device.

In addition to the embodiment described above, the present inventionalso discloses a light-output structure regarding to a light-emittingdiode chip. Please refer to FIG. 5, which shows a cross-section view ofone of the light-emitting diode chips 20 according to a preferredembodiment of the present invention. As shown in the FIG. 5, thelight-emitting diode chip comprises a non-transparent P-type electrode201; a transparent conductive layer 202; a current blocking layer 203; aP-type semiconductor layer 204; a light-emitting layer 205; an N-typeelectrode 207; an N-type semiconductor layer 206; and an opticalreflection layer 208.

Wherein, the optical reflection layer 208 is located above the substrate10, as well as at the bottom of the light-emitting diode chip; theN-type semiconductor layer 206 is located above the optical reflectionlayer 208; the N-type electrode 207 is located above the N-typesemiconductor layer 206; the light-emitting layer 205 is also locatedabove the N-type semiconductor layer 206, but not connected with theN-type electrode 207; the P-type semiconductor layer 204 is locatedabove the light-emitting layer 205; the transparent conductive layer 202is located above the P-type semiconductor layer 204, as well as on thetop of the light-emitting diode chip; in addition, the current blockinglayer 203 within the transparent conductive layer 202 is located abovethe P-type semiconductor layer 204; the P-type electrode 201 is locatedabove the transparent conductive layer 202.

Based on the structure of the light-emitting diode chip, the lightgenerated by the light-emitting layer 205 toward the bottom of the chiphas been reflected to the correct light-output direction, which isupward from the light-emitting diode chip by the reflection of theoptical reflection layer 208.

Because the current direction of the general light-emitting diode is theshortest path, most of the current injects into the region below thenon-transparent P-type electrode 201, and then generating most of thelight below the P-type electrode 201 which shielded the light,eventually resulting in reduction of light output efficiency. Therefore,the current blocking layer 203 can be used to spread the currentdirection away from the electrode 201 and improve the light emittingefficiency. The manufacture method of this kind of structure useschemical vapor deposition and etching to deposit insulators into thedevice structure for the purpose of blocking the shortest path, so as tomake the current of the light-emitting diode chip travel other paths andthus enhance the brightness or light emitting efficiency of thelight-emitting diode chip.

Refer to FIG. 6, which shows a cross-section view of the light-emittingdiode chip according to another preferred embodiment of the invention.As shown in the FIG. 6, the LED chip 30 of the embodiment includes aN-type semiconductor layer 206, an light-emitting layer 205, a P-typesemiconductor layer 204, a current blocking layer 303, a transparentconductive layer 202, a N-type electrode 207 and a P-type electrode 201.The light-emitting layer 205 is disposed on the N-type semiconductorlayer 206. The P-type semiconductor layer 204 is disposed on thelight-emitting layer 205. The current blocking layer 303 is disposed onthe P-type semiconductor layer 204. The transparent conductive layer 202is disposed on the P-type semiconductor layer 204 and covered thecurrent blocking layer 303. The N-type electrode 207 is located abovethe N-type semiconductor layer 206 and the P-type electrode 201 isdisposed on the transparent conductive layer 202 corresponding to thecurrent blocking layer 303. For example, in the present embodiment, amaterial of transparent conductive layer 202 includes an elementselected from a group consisting of indium-tin oxide (ITO), zinc oxide(ZnO), indium-gallium oxide (IGO), aluminium doped zinc oxide (AZO),nickel oxide (NiO), ruthenium dioxide (RuO₂), and graphene. Besides, inthe present embodiment, a material of the electrodes 201, 207 includesan element selected from a group consisting of metal such as Ag, Al, Au,Rh, Pt, Pd, Ni, Cr, Cu, Ti, and compound metal such as AlCu, AlSiCu,AgAl, NiAg.

In detail, in the present embodiment, the current blocking layer 303includes a plurality of high refractive index layers 303 h 1, 303 h 2and a plurality of low refractive index layers 303 lb, 303 l 1 and 303 l2, wherein the high refractive index layers 303 h 1, 303 h 2 and the lowrefractive index layers 303 lb, 303 l 1 and 303 l 2 are alternatelystacked. In this way, the current blocking layer 303 could form adistributed Bragg reflector (DBR) through the alternately stacked thehigh refractive index layers 303 h 1, 303 h 2 and the low refractiveindex layers 303 lb, 303 l 1 and 303 l 2 to reflect the light emittedfrom the light-emitting layer 205.

Further, the high refractive index layers 303 h 1, 303 h 2 include afirst high refractive index layer 303 h 1 and a second high refractiveindex layer 303 h 2, and the low refractive index layers 303 lb, 303 l 1and 303 l 2 include a low refractive index bottom layer 303 lb, a firstlow refractive index layer 303 l 1 and a second low refractive indexlayer 303 l 2. The low refractive index bottom layer 303 lb is disposedbetween the P-type semiconductor layer 204 and the first high refractiveindex layer 303 h 1. The first low refractive index layer 303 l 1 isdisposed between the first high refractive index layer 303 h 1 and thesecond high refractive index layer 303 h 2. The second low refractiveindex layer 303 l 2 is disposed between the second high refractive indexlayer 303 h 2 and the transparent conductive layer 202. In this way, thereflectivity of the light emitted from the light-emitting layer 205could be enhanced through adjusting the thickness of each of a pluralityof high refractive index layers 303 h 1, 303 h 2 and a plurality of lowrefractive index layers 303 lb, 303 l 1 and 303 l 2.

For example, the thicknesses of the low refractive index bottom layer303 lb is 1.75λ/n_(l), the thicknesses of the high refractive indexlayers 303 h 1, 303 h 2 are 0.25λ/n_(h), the thicknesses of the firstlow refractive index layer 303 l 1 and the second low refractive indexlayer 303 l 2 are 0.25λ/n_(l), the thicknesses of the low refractiveindex bottom layer 303 lb is 1.75λ/n_(l), where λ is wavelength of alight emitted from the light-emitting layer 205, n_(l) is a refractiveindex of the low refractive index layers, and n_(h) is a refractiveindex of the high refractive index layers. In other words, in thepresent embodiment, the thickness of the low refractive index bottomlayer 303 lb is larger than the other refractive index layer. By thisconfiguring, part of the light emitted from the light-emitting layer 205would be reflected by the current blocking layer 303 when incident tothe current blocking layer 303, so as to enhance the light extractingefficiency of the LED chip 30. Further, in the case of using the LEDchip 30 substantially, the light incident to the current blocking layer303 with a incident angle about 37° or more would be reflected totallybecause of the difference between the refractive index of the P-typesemiconductor layer 204 and the refractive index of the low refractiveindex bottom layer 303 lb.

For example, in the present embodiment, the light emitted from thelight-emitting layer 205 is a blue light, and its wavelength is about450 nm. Moreover, a material of the high refractive index layers 303 h1, 303 h 2 includes titanium dioxide (TiO₂) and its refractive indexn_(h) for the blue light is 2.81-2.82 when the incident light with awavelength about 450 nm. A material of the low refractive index layers303 lb, 303 l 1 and 303 l 2 includes silicon dioxide (SiO₂) and itsrefractive index n1 is 1.45-1.49 when the incident light with awavelength about 450 nm. It should be noticed that the aforementionedvalue ranges are only used as an example, and are not used for limitingthe invention. Those skilled in the art can select the material withadapted refractive index according to the wavelength of the lightemitted from the light-emitting layer 205 and the actual requirement,and details thereof are not repeated.

Besides, the current blocking layer 303 and the P-type electrode 201respectively have a first width W1 and a second width W2 in a crosssection view, and the first width W1 of the current blocking layer 303is larger than the second width W2 of the P-type electrode 201. Indetails, the ratio (W1/W2) of the first width W1 to the second width W2preferably ranges from 1.4 to 2.6. In this way, the light extractingefficiency, the luminous efficiency and the reliability of the LED chip30 could be enhanced by configuring of the LED chip 30 in the presentembodiment, as shown in FIG. 9. It should be noticed that theaforementioned value ranges are only used as an example, and are notused for limiting the invention. Details are described below withreference of FIG. 7 to FIG. 10.

Refer to FIG. 7, which shows a schematic view of light path of thelight-emitting diode chip in FIG. 6. As shown in FIG. 7, when part ofthe light 50 emitted from the light-emitting layer 205 is propagatingtoward the P-type electrode 201, the part of the light 50 could bereflected by the current blocking layer 303, the transparent conductivelayer 202 and the P-type electrode 201. On the other hand, refer to FIG.8, which shows another schematic view of light path of thelight-emitting diode chip in FIG. 6. As shown in FIG. 8, when part ofthe light 60 emitted from the light-emitting layer 205 is propagatingtoward the neighborhood of the P-type electrode 201, it would berefracted and passing through the current blocking layer 303 and thetransparent conductive layer 202. In this way, the light extractingefficiency and luminous efficiency would be enhanced.

According to the above description, please refer to FIG. 9, which showsa ratio of the first width to the second width—enhancement of lightoutput power (LOP) rate curve diagram of the light-emitting diode chipshow in FIG. 6. As shown in FIG. 9, in the present embodiment, when theratio (W1/W2) of the first width W1 to the second width W2 ranges from1.4 to 2.6, the enhancement of LOP would range from 0.55% to 0.70%. Inother words, the luminous efficiency of the LED chip 30 in the presentembodiment could be optimized by controlling the ratio (W1/W2) of thefirst width W1 to the second width W2. It should be noticed that theaforementioned value ranges are only used as an example, and are notused for limiting the invention.

Refer to FIG. 10, which shows a schematic view of current flow of thelight-emitting diode chip in FIG. 6. As shown in FIG. 10, when the LEDchip 30 illuminates, the current CF provided from the P-type electrode201 would not flow through the current blocking layer 303 but flow alongthe transparent conductive layer 202 and be transmitted to the N-typeelectrode 207 so as to decrease the probability of passing through thepart of the light-emitting layer 205 directly under the P-type electrode201. In this way, the luminous efficiency of the LED chip 30 would befurther enhanced.

Referring to FIG. 11, which shows a cross-section view of thelight-emitting diode chip according to yet another preferred embodimentof the invention. As shown in FIG. 11, the LED chip 30′ of theembodiment is similar to the LED chip 30 show in FIG. 6, and differencesthere between are described as follow. In the embodiment show in FIG.11, the high refractive index layers of the current blocking layer 303′of the LED chip 30′ further comprise a high refractive index top layer303 ht disposed between the second low refractive index layer 303 l 2and the transparent conductive layer 202. Moreover, in the presentembodiment, the thicknesses of the high refractive index layers 303 h 1,303 h 2 and the high refractive index top layer 303 ht are 0.15λ/n_(h),the thicknesses of the first low refractive index layer 303 l 1 and thesecond low refractive index layer 303 l 2 are 0.45λ/n_(l), thethicknesses of the low refractive index bottom layer 303 lb is0.6λ/n_(l).

In this way, the light extracting efficiency and the luminous efficiencyof the LED chip 30′ could also be enhanced by configuring of the currentblocking layer 303′ in the present embodiment. Besides, in the presentembodiment, the thickness of each of a plurality of high refractiveindex layers 303 h 1, 303 h 2 and 303 ht and a plurality of lowrefractive index layers 303 lb, 303 l 1 and 303 l 2 is formed withnon-integer film stacks. Herein, the non-integer film stacks means thatthe optical path difference (OPD) between the adjacent refractive indexlayers of the current blocking layer 303′ is not equal to the integertimes of the half-wavelength of the light emitted from thelight-emitting layer 205. In this way, the reflectivity of the lightincident toward the P-type electrode 201 with a small incident angle andthe transmittance of the light propagating toward the neighborhood ofthe P-type electrode 201 would be optimized. Details are described belowwith reference of FIG. 12 to FIG. 13.

Referring to FIG. 12, which shows an incident angle-reflectivity ratecurve diagram of the light-emitting diode chip show in FIG. 6 and FIG.11. Similar as the LED chip 30, in the embodiment show in FIG. 11, whenpart of the light emitted from the light-emitting layer 205 ispropagating toward the P-type electrode 201, the part of the light couldbe reflected by the current blocking layer 303′, the transparentconductive layer 202 and the P-type electrode 201. Moreover, as shown inFIG. 12, the reflectivity of the LED chip 30′ is higher and more uniformthan reflectivity of LED chip 30 when an incident angle of the lightpropagating toward the P-type electrode 201 ranged from 6 to 30 degrees.

Referring to FIG. 13, which shows an incident angle-transmittance ratecurve diagram of the light-emitting diode chip show in FIG. 6 and FIG.11. Similar as the LED chip 30, in the embodiment show in FIG. 11, whenpart of the light emitted from the light-emitting layer 205 ispropagating toward the neighborhood of the P-type electrode 201, itwould be refracted and passing through the current blocking layer 303′and the transparent conductive layer 202 of the LED chip 30′. Moreover,as shown in FIG. 13, the transmittance of the LED chip 30′ is higherthan transmittance of the LED chip 30 when an incident angle of thelight propagating toward the neighborhood of the P-type electrode 201ranged from 0 to 22 degrees.

To conclude the above, the LED chip of the invention could cause thatthe reflectivity of the light incident toward the second electrode witha small incident angle and the transmittance of the light propagatingtoward the neighborhood of the second electrode would be optimized byadjusting the thickness of each of a plurality of high refractive indexlayers and a plurality of low refractive index layers so as to enhancethe light extracting efficiency or the luminous efficiency of the LEDchip. Besides, by configuring the current blocking layer and transparentconductive layer, the luminous efficiency and the reliability of the LEDchip would be enhanced through preventing the current from passing thelight-emitting layer.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed embodimentswithout departing from the scope or spirit of the invention. In view ofthe foregoing, it is intended that the invention covers modificationsand variations of this disclosure provided that they fall within thescope of the following claims and their equivalents.

What is claimed is:
 1. A light emitting diode (LED) chip, comprising: afirst type semiconductor layer; a light-emitting layer, disposed on thefirst type semiconductor layer; a second type semiconductor layer,disposed on the light-emitting layer; a current blocking layer, disposedon the second type semiconductor layer; a transparent conductive layerdisposed on the second type semiconductor layer and covered the currentblocking layer; and an electrode, disposed on the transparent conductivelayer corresponding to the current blocking layer; wherein the currentblocking layer and the electrode respectively have a first width and asecond width in a cross section view, and the first width of the currentblocking layer is larger than the second width of the electrode, whereinthe current blocking layer comprises a plurality of high refractiveindex layers and a plurality of low refractive index layers, and thehigh refractive index layers and the low refractive index layers arealternately stacked, wherein the ratio of the first width to the secondwidth ranges from 1.4 to 2.6.
 2. The LED chip according to claim 1,wherein the high refractive index layers comprise a first highrefractive index layer and a second high refractive index layer, and thelow refractive index layers comprise: a low refractive index bottomlayer, disposed between the second type semiconductor layer and thefirst high refractive index layer; a first low refractive index layer,disposed between the first high refractive index layer and the secondhigh refractive index layer; and a second low refractive index layer,disposed between the second high refractive index layer and thetransparent conductive layer.
 3. The LED chip according to claim 2,wherein the thickness of the low refractive index bottom layer is largerthan the other refractive index layer.
 4. The LED chip according toclaim 2, wherein the thicknesses of the high refractive index layers are0.25λ/n_(h), the thicknesses of the first low refractive index layer andthe second low refractive index layer are 0.25λ/n_(l), the thicknessesof the low refractive index bottom layer is 1.75λ/n_(l), where λ iswavelength of a light emitted from the light-emitting layer, n_(h) is arefractive index of the high refractive index layer, and n_(l) is arefractive index of the low refractive index layers.
 5. The LED chipaccording to claim 2, wherein the high refractive index layers furthercomprise a high refractive index top layer disposed between the secondlow refractive index layer and the transparent conductive layer.
 6. TheLED chip according to claim 5, wherein the thicknesses of the highrefractive index layers and the high refractive index top layer are0.15λ/n_(h), the thicknesses of the first low refractive index layer andthe second low refractive index layer are 0.45λ/n_(l), the thicknessesof the low refractive index bottom layer is 0.6λ/n_(l), where λ iswavelength of a light emitted from the light-emitting layer, n_(l) is arefractive index of the low refractive index layers, and n_(h) is arefractive index of the high refractive index layer.
 7. The LED chipaccording to claim 1, wherein a material of the high refractive indexlayers include titanium dioxide (TiO₂).
 8. The LED chip according toclaim 1, wherein a material of the low refractive index layers includesilicon dioxide (SiO₂).
 9. The LED chip according to claim 1, wherein amaterial of transparent conductive layer includes an element selectedfrom a group consisting of indium-tin oxide (ITO), zinc oxide (ZnO),indium-gallium oxide (IGO), aluminium doped zinc oxide (AZO), nickeloxide (NiO), ruthenium dioxide (RuO₂), and graphene.
 10. A lightemitting diode (LED) chip, comprising: a first type semiconductor layer;a light-emitting layer, disposed on the first type semiconductor layer;a second type semiconductor layer, disposed on the light-emitting layer;a current blocking layer, disposed on the second type semiconductorlayer; a transparent conductive layer disposed on the second typesemiconductor layer and covered the current blocking layer; and anelectrode, disposed on the transparent conductive layer corresponding tothe current blocking layer; wherein the current blocking layer comprisesa plurality of high refractive index layers and a plurality of lowrefractive index layers, and the high refractive index layers and thelow refractive index layers are alternately stacked, and the number ofthe high refractive index layers and the number of the low refractiveindex layers are different.
 11. The LED chip according to claim 10,wherein the high refractive index layers comprise a first highrefractive index layer and a second high refractive index layer, and thelow refractive index layers comprise: a low refractive index bottomlayer, disposed between the second type semiconductor layer and thefirst high refractive index layer; a first low refractive index layer,disposed between the first high refractive index layer and the secondhigh refractive index layer; and a second low refractive index layer,disposed between the second high refractive index layer and thetransparent conductive layer.
 12. The LED chip according to claim 11,wherein the thickness of the low refractive index bottom layer is largerthan the thickness of the first low refractive index layer, thethickness of the second low refractive index layer, the thickness of thefirst high refractive index layer, and the thickness of the second highrefractive index layer.
 13. The LED chip according to claim 11, whereinthe thicknesses of the high refractive index layers are 0.25λ/n_(h), thethicknesses of the first low refractive index layer and the second lowrefractive index layer are 0.25λ/n_(l), the thickness of the lowrefractive index bottom layer is 1.75λ/n_(l), where λ is wavelength of alight emitted from the light-emitting layer, n_(h) is a refractive indexof the high refractive index layer, and n_(l) is a refractive index ofthe low refractive index layers.
 14. A light emitting diode (LED) chip,comprising: a first type semiconductor layer; a light-emitting layer,disposed on the first type semiconductor layer; a second typesemiconductor layer, disposed on the light-emitting layer; a currentblocking layer, disposed on the second type semiconductor layer; atransparent conductive layer disposed on the second type semiconductorlayer and covered the current blocking layer; and an electrode, disposedon the transparent conductive layer corresponding to the currentblocking layer; wherein the current blocking layer comprises a pluralityof high refractive index layers and a plurality of low refractive indexlayers, and the high refractive index layers and the low refractiveindex layers are alternately stacked; wherein the high refractive indexlayers comprise a first high refractive index layer, a second highrefractive index layer and a high refractive index top layer under thetransparent conductive layer, and the low refractive index layerscomprise: a low refractive index bottom layer, disposed between thesecond type semiconductor layer and the first high refractive indexlayer; a first low refractive index layer, disposed between the firsthigh refractive index layer and the second high refractive index layer;and a second low refractive index layer, disposed between the secondhigh refractive index layer and the high refractive index top layer; andwherein the thicknesses of the high refractive index layers and the highrefractive index top layer are 0.15λ/n_(h), the thicknesses of the firstlow refractive index layer and the second low refractive index layer are0.45λ/n_(l), the thickness of the low refractive index bottom layer is0.6λ/n_(l), where λ is wavelength of a light emitted from thelight-emitting layer, n_(l) is a refractive index of the low refractiveindex layers, and n_(h) is a refractive index of the high refractiveindex layer.